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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network40.60.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
40.60.0.0
Broadcast address
40.60.63.255
First usable
40.60.0.1
Last usable
40.60.63.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
A (default /8)
As numbers
Hex 283C0000 · Integer 675020800 to 675037183
Reverse DNS zones
0.60.40.in-addr.arpa
1.60.40.in-addr.arpa
2.60.40.in-addr.arpa
3.60.40.in-addr.arpa
4.60.40.in-addr.arpa
5.60.40.in-addr.arpa
6.60.40.in-addr.arpa
7.60.40.in-addr.arpa
8.60.40.in-addr.arpa
9.60.40.in-addr.arpa
10.60.40.in-addr.arpa
11.60.40.in-addr.arpa
12.60.40.in-addr.arpa
13.60.40.in-addr.arpa
14.60.40.in-addr.arpa
15.60.40.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00101000.00111100.00000000.0000000040.60.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network00101000.00111100.00000000.0000000040.60.0.0
Broadcast00101000.00111100.00111111.1111111140.60.63.255
Split into smaller subnets/25
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

40.60.0.0/18 makes 128 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
140.60.0.0/2540.60.0.1 to 40.60.0.12640.60.0.127126
240.60.0.128/2540.60.0.129 to 40.60.0.25440.60.0.255126
340.60.1.0/2540.60.1.1 to 40.60.1.12640.60.1.127126
440.60.1.128/2540.60.1.129 to 40.60.1.25440.60.1.255126
540.60.2.0/2540.60.2.1 to 40.60.2.12640.60.2.127126
640.60.2.128/2540.60.2.129 to 40.60.2.25440.60.2.255126
740.60.3.0/2540.60.3.1 to 40.60.3.12640.60.3.127126
840.60.3.128/2540.60.3.129 to 40.60.3.25440.60.3.255126
940.60.4.0/2540.60.4.1 to 40.60.4.12640.60.4.127126
1040.60.4.128/2540.60.4.129 to 40.60.4.25440.60.4.255126
1140.60.5.0/2540.60.5.1 to 40.60.5.12640.60.5.127126
1240.60.5.128/2540.60.5.129 to 40.60.5.25440.60.5.255126
1340.60.6.0/2540.60.6.1 to 40.60.6.12640.60.6.127126
1440.60.6.128/2540.60.6.129 to 40.60.6.25440.60.6.255126
1540.60.7.0/2540.60.7.1 to 40.60.7.12640.60.7.127126
1640.60.7.128/2540.60.7.129 to 40.60.7.25440.60.7.255126
1740.60.8.0/2540.60.8.1 to 40.60.8.12640.60.8.127126
1840.60.8.128/2540.60.8.129 to 40.60.8.25440.60.8.255126
1940.60.9.0/2540.60.9.1 to 40.60.9.12640.60.9.127126
2040.60.9.128/2540.60.9.129 to 40.60.9.25440.60.9.255126
2140.60.10.0/2540.60.10.1 to 40.60.10.12640.60.10.127126
2240.60.10.128/2540.60.10.129 to 40.60.10.25440.60.10.255126
2340.60.11.0/2540.60.11.1 to 40.60.11.12640.60.11.127126
2440.60.11.128/2540.60.11.129 to 40.60.11.25440.60.11.255126
2540.60.12.0/2540.60.12.1 to 40.60.12.12640.60.12.127126
2640.60.12.128/2540.60.12.129 to 40.60.12.25440.60.12.255126
2740.60.13.0/2540.60.13.1 to 40.60.13.12640.60.13.127126
2840.60.13.128/2540.60.13.129 to 40.60.13.25440.60.13.255126
2940.60.14.0/2540.60.14.1 to 40.60.14.12640.60.14.127126
3040.60.14.128/2540.60.14.129 to 40.60.14.25440.60.14.255126
3140.60.15.0/2540.60.15.1 to 40.60.15.12640.60.15.127126
3240.60.15.128/2540.60.15.129 to 40.60.15.25440.60.15.255126
3340.60.16.0/2540.60.16.1 to 40.60.16.12640.60.16.127126
3440.60.16.128/2540.60.16.129 to 40.60.16.25440.60.16.255126
3540.60.17.0/2540.60.17.1 to 40.60.17.12640.60.17.127126
3640.60.17.128/2540.60.17.129 to 40.60.17.25440.60.17.255126
3740.60.18.0/2540.60.18.1 to 40.60.18.12640.60.18.127126
3840.60.18.128/2540.60.18.129 to 40.60.18.25440.60.18.255126
3940.60.19.0/2540.60.19.1 to 40.60.19.12640.60.19.127126
4040.60.19.128/2540.60.19.129 to 40.60.19.25440.60.19.255126
4140.60.20.0/2540.60.20.1 to 40.60.20.12640.60.20.127126
4240.60.20.128/2540.60.20.129 to 40.60.20.25440.60.20.255126
4340.60.21.0/2540.60.21.1 to 40.60.21.12640.60.21.127126
4440.60.21.128/2540.60.21.129 to 40.60.21.25440.60.21.255126
4540.60.22.0/2540.60.22.1 to 40.60.22.12640.60.22.127126
4640.60.22.128/2540.60.22.129 to 40.60.22.25440.60.22.255126
4740.60.23.0/2540.60.23.1 to 40.60.23.12640.60.23.127126
4840.60.23.128/2540.60.23.129 to 40.60.23.25440.60.23.255126
4940.60.24.0/2540.60.24.1 to 40.60.24.12640.60.24.127126
5040.60.24.128/2540.60.24.129 to 40.60.24.25440.60.24.255126
5140.60.25.0/2540.60.25.1 to 40.60.25.12640.60.25.127126
5240.60.25.128/2540.60.25.129 to 40.60.25.25440.60.25.255126
5340.60.26.0/2540.60.26.1 to 40.60.26.12640.60.26.127126
5440.60.26.128/2540.60.26.129 to 40.60.26.25440.60.26.255126
5540.60.27.0/2540.60.27.1 to 40.60.27.12640.60.27.127126
5640.60.27.128/2540.60.27.129 to 40.60.27.25440.60.27.255126
5740.60.28.0/2540.60.28.1 to 40.60.28.12640.60.28.127126
5840.60.28.128/2540.60.28.129 to 40.60.28.25440.60.28.255126
5940.60.29.0/2540.60.29.1 to 40.60.29.12640.60.29.127126
6040.60.29.128/2540.60.29.129 to 40.60.29.25440.60.29.255126
6140.60.30.0/2540.60.30.1 to 40.60.30.12640.60.30.127126
6240.60.30.128/2540.60.30.129 to 40.60.30.25440.60.30.255126
6340.60.31.0/2540.60.31.1 to 40.60.31.12640.60.31.127126
6440.60.31.128/2540.60.31.129 to 40.60.31.25440.60.31.255126
6540.60.32.0/2540.60.32.1 to 40.60.32.12640.60.32.127126
6640.60.32.128/2540.60.32.129 to 40.60.32.25440.60.32.255126
6740.60.33.0/2540.60.33.1 to 40.60.33.12640.60.33.127126
6840.60.33.128/2540.60.33.129 to 40.60.33.25440.60.33.255126
6940.60.34.0/2540.60.34.1 to 40.60.34.12640.60.34.127126
7040.60.34.128/2540.60.34.129 to 40.60.34.25440.60.34.255126
7140.60.35.0/2540.60.35.1 to 40.60.35.12640.60.35.127126
7240.60.35.128/2540.60.35.129 to 40.60.35.25440.60.35.255126
7340.60.36.0/2540.60.36.1 to 40.60.36.12640.60.36.127126
7440.60.36.128/2540.60.36.129 to 40.60.36.25440.60.36.255126
7540.60.37.0/2540.60.37.1 to 40.60.37.12640.60.37.127126
7640.60.37.128/2540.60.37.129 to 40.60.37.25440.60.37.255126
7740.60.38.0/2540.60.38.1 to 40.60.38.12640.60.38.127126
7840.60.38.128/2540.60.38.129 to 40.60.38.25440.60.38.255126
7940.60.39.0/2540.60.39.1 to 40.60.39.12640.60.39.127126
8040.60.39.128/2540.60.39.129 to 40.60.39.25440.60.39.255126
8140.60.40.0/2540.60.40.1 to 40.60.40.12640.60.40.127126
8240.60.40.128/2540.60.40.129 to 40.60.40.25440.60.40.255126
8340.60.41.0/2540.60.41.1 to 40.60.41.12640.60.41.127126
8440.60.41.128/2540.60.41.129 to 40.60.41.25440.60.41.255126
8540.60.42.0/2540.60.42.1 to 40.60.42.12640.60.42.127126
8640.60.42.128/2540.60.42.129 to 40.60.42.25440.60.42.255126
8740.60.43.0/2540.60.43.1 to 40.60.43.12640.60.43.127126
8840.60.43.128/2540.60.43.129 to 40.60.43.25440.60.43.255126
8940.60.44.0/2540.60.44.1 to 40.60.44.12640.60.44.127126
9040.60.44.128/2540.60.44.129 to 40.60.44.25440.60.44.255126
9140.60.45.0/2540.60.45.1 to 40.60.45.12640.60.45.127126
9240.60.45.128/2540.60.45.129 to 40.60.45.25440.60.45.255126
9340.60.46.0/2540.60.46.1 to 40.60.46.12640.60.46.127126
9440.60.46.128/2540.60.46.129 to 40.60.46.25440.60.46.255126
9540.60.47.0/2540.60.47.1 to 40.60.47.12640.60.47.127126
9640.60.47.128/2540.60.47.129 to 40.60.47.25440.60.47.255126
9740.60.48.0/2540.60.48.1 to 40.60.48.12640.60.48.127126
9840.60.48.128/2540.60.48.129 to 40.60.48.25440.60.48.255126
9940.60.49.0/2540.60.49.1 to 40.60.49.12640.60.49.127126
10040.60.49.128/2540.60.49.129 to 40.60.49.25440.60.49.255126
10140.60.50.0/2540.60.50.1 to 40.60.50.12640.60.50.127126
10240.60.50.128/2540.60.50.129 to 40.60.50.25440.60.50.255126
10340.60.51.0/2540.60.51.1 to 40.60.51.12640.60.51.127126
10440.60.51.128/2540.60.51.129 to 40.60.51.25440.60.51.255126
10540.60.52.0/2540.60.52.1 to 40.60.52.12640.60.52.127126
10640.60.52.128/2540.60.52.129 to 40.60.52.25440.60.52.255126
10740.60.53.0/2540.60.53.1 to 40.60.53.12640.60.53.127126
10840.60.53.128/2540.60.53.129 to 40.60.53.25440.60.53.255126
10940.60.54.0/2540.60.54.1 to 40.60.54.12640.60.54.127126
11040.60.54.128/2540.60.54.129 to 40.60.54.25440.60.54.255126
11140.60.55.0/2540.60.55.1 to 40.60.55.12640.60.55.127126
11240.60.55.128/2540.60.55.129 to 40.60.55.25440.60.55.255126
11340.60.56.0/2540.60.56.1 to 40.60.56.12640.60.56.127126
11440.60.56.128/2540.60.56.129 to 40.60.56.25440.60.56.255126
11540.60.57.0/2540.60.57.1 to 40.60.57.12640.60.57.127126
11640.60.57.128/2540.60.57.129 to 40.60.57.25440.60.57.255126
11740.60.58.0/2540.60.58.1 to 40.60.58.12640.60.58.127126
11840.60.58.128/2540.60.58.129 to 40.60.58.25440.60.58.255126
11940.60.59.0/2540.60.59.1 to 40.60.59.12640.60.59.127126
12040.60.59.128/2540.60.59.129 to 40.60.59.25440.60.59.255126
12140.60.60.0/2540.60.60.1 to 40.60.60.12640.60.60.127126
12240.60.60.128/2540.60.60.129 to 40.60.60.25440.60.60.255126
12340.60.61.0/2540.60.61.1 to 40.60.61.12640.60.61.127126
12440.60.61.128/2540.60.61.129 to 40.60.61.25440.60.61.255126
12540.60.62.0/2540.60.62.1 to 40.60.62.12640.60.62.127126
12640.60.62.128/2540.60.62.129 to 40.60.62.25440.60.62.255126
12740.60.63.0/2540.60.63.1 to 40.60.63.12640.60.63.127126
12840.60.63.128/2540.60.63.129 to 40.60.63.25440.60.63.255126

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.